1. Field of the Invention
The invention relates to a module for a modular conveyor mat, comprising a front side and a rear side having hinge loops extending outwards relative to the module, such that in two modules succeeding each other in a conveying direction, the hinge loops on the front side of one module can cooperate with the hinge loops on the rear side of the other module and can be coupled by means of hinge pins extending transversely to the conveying direction, said module further comprising a top side, a bottom side and two lateral sides located opposite each other transversely to the conveying direction, and at least one recess accommodating a retaining member which is rotatable relative to a rotation axis extending through the retaining member, such that a closing part of the retaining member is rotatable between a first position in which the closing part can retain a hinge pin received by the hinge loops transversely to the conveying direction and a second position in which the closing part can release a hinge pin received by the hinge loops transversely to the conveying direction.
2. Description of Related Art
Such a module is used for composing a modular conveyor mat. A conventional modular conveyor mat is built up of a number of modules succeeding each other in a conveying direction and arranged side-by-side transversely to the conveying direction. Viewed in conveying direction, the modules each have their front and rear sides provided with hinge loops. The hinge loops of modules succeeding each other in conveying direction cooperate and are coupled by means of hinge pins extending transversely to the conveying direction. For retaining the hinge pins transversely to the conveying direction, the modules that are located adjacent the lateral sides of the conveyor mat are provided with a retaining member. A module having a retaining member is also referred to as `end module`, while the retaining member in assembled condition is also referred to as `retaining mechanism`.
During assembly of the conveyor mat, after two rows of modules succeeding each other in conveying direction have been coupled by means of a hinge pin, the hinge pin is retained transversely to the conveying direction between the retaining members of two end modules arranged on opposite ends of the row of modules. Disassembly of the mat proceeds in reverse order.
It is observed that an end module may comprise several retaining members, for instance when a conveyor mat comprises only one module, viewed transversely to the conveying direction.
In practice, a large number of requirements are imposed on the retaining member of an end module. The operation of the retaining member must be simple, i.e. it must be possible to carry out the operation without any special directions and/or special tools. Further, the retaining member must be insusceptible to dirt. Moreover, it must be possible to check in a simple manner whether the retaining member is in a position in which it retains a hinge pin received by the hinge loops. A further requirement imposed on the retaining member is that it does not have to be removed for enabling fitting the hinge pin, so as to reduce the risk of the retaining member getting lost. Further, the retaining member must be insusceptible to wear of the top, bottom and lateral side of the end module. Another important requirement imposed on a retaining member is that the retaining member must not impede the assembly/disassembly of the conveyor mat.
In practice, it has proved to be difficult to provide an end module that satisfies the above requirements. U.S. Pat. No. 5,335,768 discloses a module whose retaining member comprises an arm rotatable between a first position in which it can retain a hinge pin received by the hinge loops transversely to the conveying direction in that it closes the hinge hole, and a second position in which the arm can release a hinge pin received by the hinge loops transversely to the conveying direction in that the arm extends outwards relative to the bottom side of the module. As the arm extends outwards, there is the chance of the arm getting damaged, for instance when a retaining member of an end module of a moving conveyor mat accidentally adopts the second position and bumps against an obstacle. This leads to a highly reduced reliability in operation of the conveyor mat. Further, the disassembly of a row of modules of a conveyor mat already arranged on a conveyor track is rendered difficult, because the conveyor mat at the location of the end module must first be lifted from the conveyor track to enable operating the retaining member and/or the conveyor track must be provided with a space in which the arm in the second position can be accommodated. Disassembly is problematic in particular when the conveyor mat is taut. Moreover, the bottom side of the module is provided with a relatively large opening adjacent the arm, which increases the chance of the retaining member being blocked by the entrance of dirt. Further, the wall parts located adjacent the opening are relatively thin. Consequently, the chance of a wall part breaking off when catching behind something is fairly substantial, which reduces the reliability in operation of the retaining member.